[SOLVED] cause: not enough cooling for overhangs
I increased cooling on overhangs from 60% to 100%, and decreased overhang (10-25%) speed from 100% of outer wall speed to 85%. Issue went away completely and it now prints nicely 👌
I've started printing parts for my voron 2.4, and it's generally going well enough. The parts are looking pretty decent. But I'm having a hard time getting good results with overhanging sharp corners. They tend to warp upwards as seen in the photo on the left side. The prints stick well enough to the build plate and I don't have any other warping or adhesion issues.
Is this because my cooling for overhangs is too much?
I generally print with no part cooling in an enclosure. Temps are 245°C on the nozzle and 105°C on the bed, using 60° fan speed for overhangs. I'm printing on a anycubic kobra 2 with azurefilm ASA.
Try with fans disabled or slowed down and enable draft shield in the slicer. Ideally the printer would have a 60-100°C heated chamber.
100* in a chamber? Are your steppers rated for that? I’ve never went above 45
Place them outside the heated chamber.
For motors, the limit is the wire insulation so might get away with 100°C ambient. If you can't move them out there are also water-cooled extruders: https://www.dold-mechatronik.de/mebs-Hemera-WaCo-Mod-EN
The solution was more cooling. It was warping due to too much heat, I increased cooling to 100% and reduced overhang speed slightly and it now prints well.
Printing fast/without cooling can also go the other way:
By printing very fast the last layer may still be "hot" when the new layer is added. As the temperature differential is smaller there is less stress within the part once it is cooled down.
Fans are completely disabled, except for overhangs and bridges. If I disable fans for overhangs and bridges, they sag like crazy.
I doubt draft shield is going to do anything, the printer is already completely enclosed in a tent. I have around 50-55°C inside the tent.
Edit: I tried a re-print with less cooling for overhangs, it seems to exacerbate the issue significantly.
If your tent truly is that hot I'm impressed. On my 2.4 with just 2x bedfans, the chamber doesn't crack 40 degrees C after 45 minutes.
The reason why most recommend low/no cooling for ASA/ABS is due to low chamber temps.
If your chamber is that hot you should be able to crank the cooling without much concern. Print a temp tower to prove it out, and to feel out of this is a filament temp issue.
One other piece of advice for ASA: I've found that it likes consistency. I print basically all features at the same speed, other than the first layer. I suspect cooling would fall into this category too.